As per the recently defined IEEE 802.11u standard, an access point vendor is required to establish a tunnel supporting Layer 2 (L2) tunneling protocols with a service provider to provide communication services for mobile phone users. In particular, a Layer-2 Tunneling Protocol of Version 1, 2, or 3 (L2tpv1/2/3) can be used to establish these L2 tunnels. The tunnels can be used to establish a virtual local area network (VLAN) or wide area network (WAN), herein referred to as “network”, that can extend to cover many remote locations.
The VLAN or WAN is useful to coordinate many remote users under a single entity, such as a corporate client network or subnet. However, a network extending across a large number (thousands) of remote locations using L2tpv1/2/3 tunnels naturally poses a central scalability problem, which is processor intensive for one tunnel concentrator of a network operations center (NoC).
For example, there is a problem when it is desired to broadcast or multicast packets to all remote users of the network. Such packets must be replicated to provide one copy for each tunnel in the network. When the L2-tunnel concentrator at the NoC does this duplication, it loops over the list of tunnels and creates one copy of the packet for each tunnel. Obviously, where there are thousands of tunnels, this creates a burden for the concentrator.
One solution to the problem is simply to block all broadcast/multicast packets from going over tunnels (where the address resolution protocol (ARP) is handled with a proxy-ARP, etc.). However, there are some critical control packets that are multicast, such as Wireless Network Management Protocol (WNMP) control packets. Blocking these WNMP packets severely limits the ability to facilitate roaming and load balancing wireless clients across access points (APs) that are at a single physical location but not sharing any infrastructure between them. For example, a service provider telephone company (telco) could deploy two APs in two adjacent stores in a shopping mall each having its own network link. The two APs will Layer 3 (L3) adopt to the telco NoC concentrator, each having L2-tunnels to the NoC to tunnel all user traffic, but the APs do not know anything about each other (they are not neighbors), thereby requiring separate links. This use case is important because most of the wireless hotspot/guest-access deployments are going to look the same and have the same type of deployment when they are commissioned and operated by a telco. Another problem with this approach is it does not offer any control over how unicast traffic is controlled among the sites, in that all clients in all sites can potentially talk to each other, creating traffic and overhead problems.
Another solution to the problem is to turn off inter-tunnel bridging at the NoC L2-tunnel concentrator, i.e., packets coming from one L2 tunnel will not be sent to other L2 tunnels. However, this solution has the same problems described above for the first solution. In addition, a WNMP roam notification coming in from one AP will not be sent to any other AP, including an AP that is nearby, which will delay handoffs of mobile devices. Another problem with this solution is that it blocks any unicast communication from happening between two clients on two different APs (across two different L2 tunnels).
Hence, there is a need of a system and method to provide improved control over how data is bridged in these kinds of very large L2 tunneled deployments in a network.
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.